In the conventional semiconductor packaging processes, a substrate strip is used as a chip carrier for mounting a plurality of chips to meet the requirements of lower cost and mass production. The molding area on the substrate strip includes a plurality of packaging units arranged in an array. After semiconductor packaging processes such as die attachment, electrical connections, and molding, the substrate strip is singulated along the scribe lines between the package units to form a plurality of semiconductor packages. During handling and transporting of the semiconductor packaging processes, cracks will form on the side rails of the substrate strip due to stresses and friction. Moreover, the cracks grow due to more exerted stresses and extend into the molding area of the packaging units leading to damages of the electronic devices such as chips disposed on the packaging units.